1. Field of the Invention
The present invention relates to a printed circuit board, and in particular to a printed circuit board with an external terminal.
2. Description of the Related Art
A printed circuit board has a structure configured by forming a conductive layer on an insulation layer, such as a core layer, and forming a circuit pattern on the conductive layer. Such a printed circuit board may be employed in an electronic apparatus, such as a computer, a portable electronic terminal, etc., in which a plurality of electronic parts are integrated.
The above-mentioned circuit pattern may include a plurality of internal terminals for connecting electronic parts, and one or more external terminals electrically connectable to an external electronic apparatus or a printed circuit board of a counterpart.
FIG. 1 is a cross-sectional view showing a printed circuit board according to the prior art. Referring to FIG. 1, the conventional printed circuit board includes a core layer 110, an insulation layer 12 1 formed on the core layer 110, an elastic portion 122 inserted into the insulation layer 121, and a circuit pattern formed on the elastic portion 122 and the insulation layer 121.
The circuit pattern includes a plurality of external and internal terminals 131a and 131b; 132a and 132b, providing electric contacts. The external terminals 131a and 131b can be formed on the elastic portion so as to provide electric contacts with a counterpart printed circuit board or an external electronic apparatus.
The elastic portion 122 may be embedded in the insulation layer or exposed at the top thereof, and provides elasticity to the external terminals 131a and 131b so that the electric contacts with external devices are continuously maintained.
In the formation of printed circuit board 100, the insulation layer 121 is grown on the core layer 110, and then a part of the insulation layer 121 is selectively removed. The elastic portion 122 is formed in the previously removed portion of insulation layer 121. The elastic portion 122 may provide elasticity to the external terminals formed on the top of the elastic portion 122.
However, the elastic portion 122 and the external terminals 131a and 131b on the printed circuit board can peel off due to accumulation of fatigue and excessive physical force due to depressing and degradation of elasticity. In order to minimize this problem, a spiral contact process may be employed, which separately forms the circuit pattern and the core layer and assembles them with lamination. However, this process is difficult in alignment, and is complicated.